1. Field of the Invention
The present invention relates to a linear actuator. More particularly, but not exclusively, the present invention relates to a linear actuator having a drive arm and an extension arm which are interengaged by threads the ridge of one thread abutting both sides of the corresponding groove of the other thread.
2. Description of the Related Art
Linear actuators which convert rotary motion into linear motion are known. Simple linear actuators wherein the components are coupled together by threads tend to suffer from a degree of backlash. In some applications, for example where the linear actuator is being used to position a tuning member in a microwave resonant cavity, the uncertainty in position in the end of the actuator arm due to this backlash can be a significant effect. Linear actuators which compensate for the effects of backlash are also known. Such actuators however tend to be complex and expensive devices including optical or electrical feedback circuits.